I have an fonts.conf file, which is a valid XML file. But when I open it with Kate or KWrite, it is recognized as Bitbake. Here are many other file types that were recognized as Bitbake. I guess here are some problems with the Bitbake syntax file.
See patch https://phabricator.kde.org/D6810
This was just fixed by Guo, see https://phabricator.kde.org/D6810. Thanks for the fix, Guo!